1. Technical Field
The present invention relates to a transmission interface and a device comprising the same, and relates more particularly to a transmission interface having a quick burst motion readout mechanism and a device comprising the same.
2. Related Art
Optical mice determine their movement relative to the tracking surface underneath them by using a light source and an image sensor. FIG. 1 schematically shows a conventional optical mouse. As shown in FIG. 1, a conventional optical mouse comprises a microprocessor 11 and an optical detection module 12 connected with the microprocessor 11 using a serial peripheral interface bus 13. Generally, the serial peripheral interface bus 13 is a four wire serial bus or a two wire serial bus. The microprocessor 11 can acquire displacement data generated by the optical detection module 12 via the serial peripheral interface bus 13.
FIG. 2 is a schematic timing diagram where a read operation takes place on a serial peripheral interface bus, which is a two wire serial bus. When the serial peripheral interface bus 13 is a two wire serial bus, the serial peripheral interface bus 13 may have a SCLK (serial clock) line and a SDA (serial data) line. The microprocessor 11 and the optical detection module 12 may be configured to mutually transmit eight byte data. The microprocessor 11 provides clock signals via the SCLK line. Every time, the microprocessor 11 reads displacement data (eight byte data), which includes two synchronization bytes, two bytes for updating data, and four bytes of displacement data, wherein the two synchronization bytes and the two bytes for updating data both have to include address data 21 and 22, which includes address data 23 related to an x displacement value and address data 24 related to a y displacement value. When the transmission rate is 200 kHz, it takes 355 microseconds for complete transmission of 8 bytes of data. Although the two wire serial bus uses less input and output ports and is cheaper, it takes a longer time to transmit displacement data and cannot ensure that the displacement data is transmitted in synchronization.
FIG. 3 is a schematic timing diagram where a read operation takes place on a serial peripheral interface bus, which is a four wire serial bus. When the serial peripheral interface bus 13 is a four wire serial bus, the serial peripheral interface bus 13 may comprise a SCLK (serial clock) line, a MOSI (master output slave input) line, a MISO (master input slave output) line, and a SS (slave select) line. Every time the microprocessor 11 reads displacement data, the microprocessor 11 sets the SS line to a low logic level, issues clock signals via the SCLK line, sends address data (31, 32 and 33) and data to the optical detection module 12 via the MOSI line, and receives update data, x displacement data and y displacement data from the optical detection module 12 via the MISO line. Because there is no requirement of transmitting synchronization data, the transmission time is shorter. For example, if the transmission rate is 200 kHz and the guide time is 5 microseconds, it takes 265 microseconds for complete transmission of eight bytes of data. The four wire serial bus uses more input and output ports, is more expansive, and still spends a long time to transmit data.